I would like to set up a network with some computers I have, where they can connect to one main source, then receive and send messages back to it. I have never done any network programming before, so I'm just wondering what are the best tutorials using Ruby that I could use.
Thanks in advance.
There are about a billion ways you could do this. Could you post more about what the problem is you're trying to solve, or what the content/purpose/size/format/etc. of the messages is to be? Are you building something "for real" or just trying to learn network programming?
Also, do you already have the lower layer stuff figured out? You have networking infrastructure setup, IP addresses assigned, etc? If not, you'll need to get through that. Once you have that, you could start with a tutorial on basic socket programming in Ruby, but - depending on the answers to the questions above - you might not want to "roll your own" solution at that level. The answer might be to use an XMPP (Jabber) server, and use an XMPP client library, or you might want to deploy something like ActiveMQ, HornetQ, etc. and use a library for interfacing with that. Or maybe you want to use HTTP and pass messages around in JSON, or XML or $WHATEVER. In short, there are a LOT of options in this area.
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I'd like to start investigating client/server communication. I've started to look at Distributed Objects and a tad at CFNetwork. Let's just say I'm looking for something more my speed (which is slower).
I'd like to be able to send a message from one computer to another, possibly carrying a string or some other type of data. I'm thinking of building a simple student response system where one computer is acting as a server and the clients are connecting and sending data to it.
I'm looking for resources that might help me out as well as suggestions of where to start understanding the concepts involved. I've been teaching myself Objective-C and am a relative newbie to programming, so I know I have holes in my understanding.
"Sockets" is the canonical answer.
If you're interested, here's a great introduction to socket programming (biased toward C, but still very informative):
Beej's Guide to Network Programming
Another way of doing it really simple is by letting the server set up a local http server (inside it self), and then let the clients simply make http requests. By doing that you let the http layer do all the fancy sockets stuff. More simple, and with more overhead, but may be suitable for your case. Also a lot easier to debug, since you can use your browser to test the connection. There are many ways of implementing a HTTP server in cocoa, can't remember which one i've used, but a quick google pointed me at this one for example
before I start I realise there are a few SNMP related questions here already but not many seem to have been answered - that could mean I'm asking in the wrong place but I don't know where else to go at the moment.
I've been reading up as best I can on SNMP for a couple of days but am finding it difficult to get my head around what is meant to be happening. The idea is eventually we will integrate SNMP into our Java application server which will allow the end users to incorporate it into their pre-existing Network Management Systems(NMS).
Unfortunately I'm feeling entirely confused by what is meant to be going on. From what I understood from talking to the end users (which was unfortunately before any research) was that the monitoring allows their existing NMS to give their admin guys a view of the vital statistics in a tree type display, giving them feedback regarding different parts of the system at a high level and allowing them to dig down into specific subsystems.
From reading around we would implement an 'Agent' which has several defined interfaces allowing for GET requests etc to be processed and responded to. That makes sense but I am at a loss to work out what the format of the communication is - there don't seem to be any specific examples of what any of the messages look like, how the information is encoded.
More of my confusion though is regarding Management Information Base(MIB). I had, wrongly, assumed that the interface of the agent would allow for the monitored attributes to be requested and then in turn the values for those attributes requested. Allowing any new Agent to be started and detected without any configuration on the NMS end (with the exception of authentication in v3). This, if I understand correctly, is not the case and the Agent must instead define MIBs which can be used by the NMS to determine those attributes. My confusion is increased when people start referring to thousands of existing MIBs and that they can be reused which I don't understand. Is the intention that a single MIB definition can be used to say describe how a particular attribute of a network device (something simple like internet connected on a router:yes/no) for many different devices? If so I don't believe that our software would allow the monitoring of anything common to any other device/system but should we be looking for already exising MIBs? At the moment I don't really see any good rational for such a system, surely it would be easier for the Agent to export that information - so I'd appreciate it if someone could enlighten me!
I think it would help if I was able to setup a simple SNMP agent and some sort of client, I could begin to see the process and eventually inspect the communication between the two but am finding it difficult to find anywhere that provides any information on doing such a thing. Nagios has been recommended to us as a test 'client'/NMS but their 'get started quick' section recommends downloading a 600Mb virtual machine - surely there is a quicker way to get started?
Any help or suggestions will be appreciated, I have been through the Wiki page but it doesn't seem to go into much detail about the MIBs and the having not had to deal with anything like the referenced RFCs before, while they may contain all of the information they seem completely impenetrable to me at the moment. Or if there are any books that can be recommended for an overview and implementation of v3?
Thanks for reading and even more thanks if you think you can help!
It seems to me that you read all SNMP information piece by piece in an disorganized way. This is highly not recommended and of course lead you to confusion.
What about forgetting what you have learnt so far and dive into a good book such as Essential SNMP?
http://shop.oreilly.com/product/9780596008406.do
Click the Google Preview icon to preview it please.
You could not depend on a network forum to tell you the ABCs, as that's impractical I find out.
The communications interface is SNMP. That's the protocol used for transmission (usually on top of UDP). The thing that services information requests is an SNMP Agent. The thing that sends information requests is an SNMP Manager.
The definition of what information should be made available by the Agent, and requested by the Manager, goes in a MIB. A MIB is the "glue", a directory of what sort of things any particular system can/should offer. It maps numeric codes to names and types that allow us to make sense of the data, much like how a phone directory maps phone numbers to people's names and addresses.
Generally you would create and ship and use your own MIBs that can describe aspects specific to your own product, but you are supposed to service some standard information requests as well, which are defined in existing MIBs. Yes there are thousands of other pre-existing MIBs and the likelihood that you need more than one or two of these is remote. They are typically published versions of MIBs for existing products.
The conventional way to "toy around" is to install Net-SNMP (a software suite that includes an agent implementation and allows you to "bolt on" your own logic and your own MIBs fairly easily) then examine the results using a packet capturer like Wireshark.
For a fuller implementation in production you may stick with Net-SNMP, or write your own Agent software, or do what I did and create a hybrid of the two that's a little more flexible and performant but uses Net-SNMP's backend for handling all the low-level SNMP stuff.
Your first step, though, is to read a book or some other teaching material that can clear all your misconceptions, because guesswork won't cut it.
I had success using the samples from this page. Both the shell and Perl NetSNMP code was very straightforward to implement and query.
I'm building an application that will provide a service to other applications (let's pretend like it solves differential equations). So my DifEq service will be running all the time and a client application can send it requests to solve DifEqs at any point.
This would be trivial using sockets or pipes.
The problem is some applications nefariously want to send linear equations instead of differential equations, so I want to register applications that I know are sending proper DifEqs to my application.
Traditional sockets break down here, as far as I know.
Ideally, I'd like to be able to look at some information about the application that is making a request of me and (either through some meta-data on that application, through communication with my web site, or through some other, unkown method) determine it is an acceptable DifEq app. Furthermore, this ideal method would not be spoofable without a root/admin-level compromise of the underlying OS. If the linear equation app is also a root kit, I'll concede to being broken. :)
I need to be able to do this on Windows, OS X, and Linux (and maybe Android); but I recognize that it may not be the same solution on all platforms. So, how would you accomplish this (specify the platform you are focusing on, if appropriate)? I've done a lot of server-side development, but it's been way too many years since I've done any client-side development outside the browser and the world is very different today than it was then.
I think your question is a little confusing when it comes to talking about DifEQ vs LinearEQ.
It sounds to me like you are just looking for a routine way to verify that clients are authorized to connect. There is a lot to read up on this subject. Common methods would be to use SSL certificates to verify the identity of clients. You can also tunnel over SSH, or use OAUTH, etc, etc.
You'll have to do some more digging around the web to see what kind of authentication fits your scenario. You mention 'not spoofable'. I think that people generally end up compiling-in a certificate of private key into their application. This will stop all but the very dedicated and experienced hackers.
I've been looking around for something like this for a while, but I can't find anything.
I just want an example of a really really basic server/client with CF networking in cocoa.... there's a lot of stuff out there thats like super convoluted etc - there's got to be a clean, simple way to just set up a server, have a client send it like a number, say "1", and then return the number recieved +1 or something really rudimentary like that
i just feel like it can't possibly be that hard to send a server a number and have the server relpy with another number..
i've got some experience with c/c++/obj c but i'm not too great.
Thanks!
you should refer this CFNetwork Programming Guide. This book is intended for developers who want to use network protocols in their applications. In order to fully understand this book, you should have a good understanding of network programming concepts such as BSD sockets, streams and HTTP protocols. Additionally, you should be familiar Mac OS X programming concepts including run loops.
what's the best way to pass data between two ruby programs over the internet? The data is small and needs to be passed frequently. Also, since this happening over the internet, it needs to be secure. I'd appreciate any help, extra points for a pointer to some guides on this topic.
You can use sockets to communicate between two ruby programs ...
https://www6.software.ibm.com/developerworks/education/l-rubysocks/l-rubysocks-a4.pdf
For security use encryption